The invention relates generally to gas turbine engines and, more particularly, to fan containment casings for gas turbine engines.
Gas turbine engines typically include high and low pressure compressors, a combustor, and at least one turbine. The compressors compress air, which is mixed with fuel and channeled to the combustor. The mixture is then ignited for generating hot combustion gases, and the combustion gases are channeled to the turbine, which extracts energy from the combustion gases for powering the compressor, as well as producing useful work to propel an aircraft in flight or to power a load, such as an electrical generator.
When engines operate in various conditions, foreign objects may be ingested into the engine. More specifically, various types of foreign objects may be entrained in the inlet of a gas turbine engine, ranging from large birds, to hailstones, sand and rain. The foreign objects may impact a blade resulting in a portion of the impacted blade being torn loose from a rotor. Such a condition, known as foreign object damage, may cause the rotor blade to pierce an engine casing resulting in cracks along an exterior surface of the engine casing. Additionally, foreign object damage may cause a portion of the engine to bulge or deflect resulting in increased stresses along the entire engine casing.
At least some known engines include a metallic casing shell to prevent foreign objects and engine fragments from escaping the engine and to increase the radial and axial stiffness of the engine. Casing shells are typically fabricated from a metallic material and are one of the heaviest components in a gas turbine engine. It is highly desirable to reduce the weight of such shells through the use of less dense materials. U.S. patent Ser. No. 11/020,483, entitled “Composite fan containment case for turbine engines,” discloses a composite fan containment case that combines exceptional impact resistance and damage tolerance properties with significant weight reduction relative to metal casings. However, it would be desirable to provide a relatively low-cost, light-weight fan casing with high-impact resistance. It would further be desirable to provide a method of manufacture for the fan casing that does not require a subsequent infusion of resin. It would further be desirable for the method of manufacture to avoid a secondary bonding process.